Control of rotating wing aircraft



April 6, 1948. c. F. HODSON CONTROL OF ROTATING WING AIRCRAFT 3 Sheets-sheaf 1 Filed March 8, 1946 I IN VEN 7-01? C/YflRLfS FR/V/VC/S HUDSON,

April 6, 1948.

c. F. HODSON CONTROL OF ROTATING WING AIRCRAFT Filed March 8, 1946 5 Sheets-Sheet 2 April 6,1948. c. F. HODSON CONTROL OF ROTATING WING AIRCRAFT j Filed March 8, 1946 3 Sheets-Sheet 3 Patented Apr. 6, 1948 N D ATES V 2,439,089 7 :zGGNTRQLtQE'ROT-ATING*IWING-AIRGRAEFT TChai'les FrancisHodson, Burnham, England, as- V fsig nortoYlhe Fairey Avi'ation"Comp'any,'Lixn- Q ited,=Hayes,-Middlesex,England Application: March 8, 1946, :Serial: No.165351s1-3 In -Great Britain May- 22,1944

-1 Olafin.

"Ini'sunventionrel'atestothe-'c'ontrolling'means forthepitchchanging mechanism or'a rotating wing'aircraftand has for'its object "automatically bar being arranged. to bring about "variation of the pitch of the rotor blades collectively and movement of said=bar about zsaidlpoint being arranged to bring about cyclic pitch control of the rotor-blades.

According to the present invention the baris universally jointed to a vertically movable rod and also connected, by arms extendin integrally therefrom in planes substantially at right angles *to-'one another, with 'two further vertioally movable rods, the first movable rod being operatively connected with the inching valve of a hydraulic jack for varying the pitch of the rotor blades collectively and each of the two vertically movable rods being connected with an appropriate inching valve of a hydraulic jack for effecting cyclic pitch control of the rotor blades. It is a principal object of the invention to provide such a structure.

One form of the invention is illustrated by the accompanying drawings wherein Figure 1 is a quasi-diagrammatic side elevation of the improved controlling means and Figure 2 is a fragmentary elevation thereof as seen from the left, t

Figure 1, parts being shown in section in both views. Figure 3 is a horizontal sectional view taken on a line (not shown) passing slightly above blades a.

As shown, the blades, indicated at a of a four-bladed rotor are arranged to flap about axes passing through a common point b lying on the general axis of rotation of the rotor mechanism and are connected by supporting links 0 with a bar d universally jointed at its lower end as at e on the top of a vertically movable rod ,f coaxially arranged on guides go slidable within the hollow shaft h of the mechanism. The supporting link 0 of the blades a are not connected directly with the bar (I but each pair of diametrically opposite supporting links cc is connected pivotally with an appropriate collar 5i slidable on said bar d between a pair of coiled springs km, km, three abutments n, o, p for the springs being integral with the bar d, the central abutment 0 serving in common for the lower spring is of the upper pair and the upperspring m of the lower pair.

Projecting radially from the bar 12 in planes at right angles to one another, with their axes intersecting at the centre e of the universal joint at the bottom of the bar d, are two arms qr which,

with the Tbar it, constitute :two lbell crank "levers rockable in intersecting planes about the centre c andat "their freeendslthesearms qr are connected by links .s't with two further vertically movable rods tic-arranged eccentrically and slidably i'n'the-guid'esgg within-the hollow shaft h ofthe mechanism.

The vcrticallymovable rod 7 is connected atits lower end with the inching valve w of an hydraulic jacks," arranged to raise and lower a sphericatbearingyior a swash plate a" connected witlimeans'including arms 596, l, 8 for'varying' the-pitch "ofthe rotor'arms "a collectively. The verticallymovable rod'u i's connected at its lower end'with-"one arm I I of a bell crank lever H, t2 the ther'arm [20f which projects into; and has a slidable connection with, a tubular head l 3 on the-"plunger I i-of aninching valve 15 of anhydraulic ja cklfi for varying the pitch of the rotor blades a cyclically, the axis of the tubular head l3 being at right angles to that of the plunger l4 so that rocking of the bell crank lever H, I2 is converted into axial movement of the plunger M of the inching valve 15. Similarly, the vertically movable rod 12 is connected atv its lower end with one arm I! of a bell crank leverl1, l8 the other arm l8 of which projects into, and ha a slidable connection with, a tubular head IS on the plunger 20 of an inching valve 2| of an hydraulic jack (not shown, but lying in a radial plane at right angles to that in which is situated the jack [6) also for varying the pitch of the rotor blades a cyclically, the axis of the tubular head 19 being at right angles to that of the plunger 20 so that rocking of the bell crank lever l1, I8 is converted into axial movement of the plunger 20 of the inching valve 2|. The cylinders of all three inching valves 11), I5 and 2| are connected, the valve to by a bell crank lever 22, 23 and link 24, the valve [5 by a link 26 and the valve 2| by an arm 21 on a torque tube 28, with means (not shown) under the control of the pilot so that, apart from automatic control, to which reference will be made hereinafter, the pilot can effect pitch control of the rotor blade a either collectively or cyclically.

The arrangement is such that when, under the action of the lift force acting on the blades or they tend to move upwards about the common flapping pivot point 1), their supporting links 0 compress the upper springs m of each pair. If the upward flap of all the blades a be equal the bar cl will rise vertically taking with it the vertically movable rod 1 and thus operate the inching valve 20 of the collective pitch varying jack :1; to bring about a general reduction of thepitch of the rotor blades a with consequent increased rotational speed and reduction of the flap angle of the blades until some static position be found.

thereon their links st, vertically movable rods 1w bell cranks II, I 2 and I1, I8 and their inching valves [5 and 21 as a unit, to advance or retard Q the cyclic pitch change operation with regard to the sideways or forward movement of the com: mon abutment o for the supporting link springs.

If the blades a of the rotor do not move in a path which lies on the surface of a cone the distance between the collars 7'7 to which the supporting links 0 are pivoted will vary continuously and, if desired (although not shown), this variation may be used to operate through a commutator or interceptor valve the inching valve of a further hydraulic jack which in turn may operate an infinitely variable cam and tappet arrangement replacing the swashplate z, and giving an irregular cyclic pitch change. The phase angle of these irregularities may be advanced or retarded by rotating the cam and/or the commutator or intercepter valve about their vertical axis. 1

If the rotor has only three blades their supporting arms 0 may be pivoted directly to the valve of an hydraulic jack forvarying the'pitch.

bar d and the springs km and collars :i eliminated.

Iclaim: i 1

Controlling means for the pitch changing mechanism of a rotating wing aircraft wherein the rotor blades are connected by supporting links with a bar which is mounted for vertical movement and also for universal movement about a point, vertical, movement of said bar being arranged to bring-about variation of the pitch of the rotor blades collectively and movement of said bar about said point being arranged to bring about cyclic pitch control of the rotor blades, wherein the bar is universally jointed to a vertically movable rod and is also connected, by arms extending integrally therefrom in planes substantially at right angles to one another, with two further vertically movable rods, thefirst movable rod being operatively connected with the inching REFERENCES" crrED The following references are of record in the file of this patent: r

UNITED STATES PATENTS Number Name Date 2,408,489 Stalker Qct. 1, 1946 

